Oceans No Longer as Effective at Storing Carbon Dioxide

Long considered to be the planet's ultimate safety valve for excess carbon dioxide - drawing down close to 25% of all anthropogenic emissions - the oceans may not prove as effective at storing the greenhouse gas as they did during the last ice age, almost 20,000 years ago. As a result, scientists are worried that global warming's onset may prove much faster than originally expected - particularly if temperatures continue to rise at current rates.

Eric Galbraith and a team of researchers from the University of British Columbia looked at cores of sediment taken from the ocean floor in the North Pacific dating back to the last ice age. By carbon dating foraminifera shells contained within the cores, Galbraith and his colleagues determined that the slow movement of the deep ocean was even more so 20,000 years ago - leading them to conclude that it took longer for the absorbed carbon dioxide then to turn over and return to the surface (3,000 years vs. 2,000 years now).

In other words, the oceans were able to store carbon dioxide for longer periods of time. The researchers also discovered that the deep ocean was able to sequester more of the GHG back then. This could prove problematic if the planet starts warming up too much, says Galbraith, as it could cause the oceans' biological pump to eventually collapse.

"We've been benefitting from this pump that's in the ocean, pumping the CO2 into the deep sea," he said. "If the last ice age was a good analogy, this pump is not going to function as well in the future... That it won't take up as much CO2 as it has in the past. The numbers we're talking about are so big they could have big impacts on the outcome of climate change."

Long considered to be the planet's ultimate safety valve for excess carbon dioxide - drawing down close to 25% of all anthropogenic emissions - the oceans may not prove as effective at storing the greenhouse gas as they did during the last ice age,